Re: [Gimp-developer] scheme changes

2007-04-16 Thread Kevin Cozens
Jim Sabatke wrote:
> I understand 
> that gimp has migrated to tiny scheme and variables need to be declared 
> with let or let*.  I have tried and tried to modify some of the scripts 
> and can't get them to work.
[snip]
> The documents on the let and let* functions make it seem like I 
> shouldn't be having this much trouble.

I realize that Scheme code looks rather cryptic to a lot of people but, no, 
you shouldn't be having that much trouble.

What doesn't help matters is that a lot of Scheme code is poorly formatted 
making it look like something suitable for submission to an Obufuscated Scheme 
contest. When the code is properly formatted it is much easier to see the 
syntax of the lanuage. This also makes it easier to modify Scheme code and 
eliminates so much of the time one otherwise spends counting brackets.

As someone else mentioned, you can "cheat" and just change the 'set!' calls to 
'define'. However, putting the undefined variables in a let/let* block is 
preferred.

A let block looks like the following:
(let* (
   (var1 value-or-code-to-give-initial-value-for-variable)
   (var2 some-other-value)
   )
   ... scheme code ...
)

If your script gives you an error message along the line of 'unbound variable: 
bad-var', you just need to add 'bad-var' to the let block.

(let* (
   (var1 value-or-code-to-give-initial-value-for-variable)
   (var2 some-other-value)
   (bad-var)
   )
   ... scheme code ...
)

You don't have to even have to specify a value if you don't want to. 
Alternatively, you could take the entire Scheme set! statement where bad-var 
is first used and put it in the header without the leading set! command where 
I showed '(bad-var)'.

--
Cheers!

Kevin.

http://www.ve3syb.ca/   |"What are we going to do today, Borg?"
Owner of Elecraft K2 #2172  |"Same thing we always do, Pinkutus:
 |  Try to assimilate the world!"
#include  |  -Pinkutus & the Borg
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Re: [Gimp-developer] scheme changes

2007-04-16 Thread Simon Budig
Renan Birck Pinheiro ([EMAIL PROTECTED]) wrote:
> Em Sáb, 2007-04-14 às 18:37 -0500, Jim Sabatke escreveu:
> > I have a lot of scripts that no longer work under 2.3.x.  I
> > understand that gimp has migrated to tiny scheme and variables need
> > to be declared with let or let*.  I have tried and tried to modify
> > some of the scripts and can't get them to work.  I've looked at
> > examples of scripts that do work and I've gone over (and over) the
> > syntax for 'let' in my Lisp books, all to no avail. 
> 
> This might or might not be what you want, but for most of my scripts,
> replacing "set!" by "define" worked. 

I do believe that properly scoping the variables within a let*-block
would be more appropriate here. However, I really cannot tell without
looking at the problematic scripts. I'd be glad to discuss the issues on
this list, if someone could summarize this into a tutorial or something
I'd be glad to put it on the website.

Bye,
Simon
-- 
  [EMAIL PROTECTED]  http://simon.budig.de/
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Re: [Gimp-developer] scheme changes

2007-04-14 Thread Renan Birck Pinheiro
Em Sáb, 2007-04-14 às 18:37 -0500, Jim Sabatke escreveu:
> I have a lot of scripts that no longer work under 2.3.x.  I
> understand 
> that gimp has migrated to tiny scheme and variables need to be
> declared 
> with let or let*.  I have tried and tried to modify some of the
> scripts 
> and can't get them to work.  I've looked at examples of scripts that
> do 
> work and I've gone over (and over) the syntax for 'let' in my Lisp 
> books, all to no avail. 

This might or might not be what you want, but for most of my scripts,
replacing "set!" by "define" worked. 

I found this hint, but is in Portuguese:

http://cadafalso.deusexmachina.com.br/2007/01/17/erros-no-gimp-2313/

hth,
Renan "Renan_S2" Birck

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[Gimp-developer] scheme changes

2007-04-14 Thread Jim Sabatke
I have a lot of scripts that no longer work under 2.3.x.  I understand 
that gimp has migrated to tiny scheme and variables need to be declared 
with let or let*.  I have tried and tried to modify some of the scripts 
and can't get them to work.  I've looked at examples of scripts that do 
work and I've gone over (and over) the syntax for 'let' in my Lisp 
books, all to no avail.

I have also searched the archives for this email list for clues.

Has anyone produced a simple to understand document on how to use those 
functions on misbehaving scripts?

The documents on the let and let* functions make it seem like I 
shouldn't be having this much trouble.

TIA

Jim
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